1. Technical Field of the Invention
The present invention relates to a electrical junction box in which a screw-tightening type fusible link, external relay boxes or the like are attachable to a junction box main body in which various kinds of wiring members are provided.
2. Background of Related Art
Nowadays, automobiles include different kinds of electrical parts to control driving thereof including, for instance, relay switches, fusible links and so on. The electrical parts are mounted on an electrical junction box, and the electrical junction box and electrical devices are connected by wire harnesses. Although there are various kinds of structures for such an electrical junction box, the following is a description of a mounting structure of a screw-tightening type fusible link disclosed in the Unexamined Japanese Utility Model Publication Sho. 63-127055, with reference to FIGS. 6-8.
On a top face of a main body 51 of a junction box as shown in FIG. 6, a plurality of housings 52 for mounting relays, a plurality of housing 53b for mounting fusible links and a housing 53a for mounting a fusible link are formed.
At a corner of the main body 51, an outer corner wall 54 which is inclined with respect to outer walls 51a, 51b is formed, and a projected portion 55 is formed so as to be perpendicular to the outer corner wall 54. An external relay box mounting housing 53a is provided in a position corresponding to the projected portion 55 on a top face of the main body 51. Nut members 56a, 56b are adherely fixed on both sides of the projected portion 55 in a predetermined position under the fusible link mounting housing 53a as shown in FIG. 8. Further, a bus bar 57 is provided on the nut member 56a in one side of the projected portion 55. The bus bar 57 is branched off and lead to the fusible link mounting housings 53b.
A fusible link 58 shown in FIG. 6 is a screw-tightening type which is used when a high current-carrying capacity in a range of 60-100 A is required. For the case of a low current-carrying capacity in a range of 30-50 A, a terminal-engaging type fusible link is used. On a lower face of the fusible link 58, two leg portions 59a, 59b are projectingly provided, and screw holes 60a, 60b for screw-tightening are formed respectively in each of the leg portions 59a, 59b.
When the fusible link 58 is mounted onto the fusible link mounting housing 53a, the leg portions 59a, 59b pierce through a bottom of the housing 53a and are positioned at both ends of the projected portion 55. After that, the screw hole 60a in one leg portion 59a is met with the nut member 56a of the projected portion 55, and a predetermined wiring, namely, a circular terminal 61a of wire harness, is secured with a bolt 62 onto the nut portion 56a through the bus bar 57. As a result, the leg portion 59a, the bus bar 57 and circular terminal 61a are electrically connected.
Besides, another circular terminal 61b of the wire harness that is connected to loads is connected with the other leg portion 59b by securing the other nut member 56b with a bolt 62. To secure the nut members 56a, 56b with the bolts 62, 62, a monkey wrench shown in FIG. 6 or an impact wrench 64 shown in FIG. 8 is utilized.
In the conventional mounting structure of fusible link, other parts such as an external relay box, a battery, an air cleaner or the like are disposed in the vicinity of the main body 51 and the wire harnesses having the circular terminals 61a, 61b are connected with such parts. Hence, when the electric junction box is disposed in a automobile, it is necessary to provide a space for operating the monkey wrench 63 in the vicinity of an arrow A if the monkey wrench 63 is utilized for tightening the bolt 62. If the impact wrench 64 is utilized for the tightening, it is necessary to provide a space as well in the vicinity of an arrow B.
In the conventional electrical junction box, however, there are some cases where the impact wrench 64 or the like cannot be used because it falls on other parts such as the battery and so on and, thus, keeping the operation space becomes impossible.
In such a case, it is necessary to change the order of disposing the electrical junction box into the automobile, thus causing compromises in operational efficiency due to the necessity of changing design or assembling process.
Other then securing the circular terminals with the bolts, utilizing a connector to connect one wire harness with the other harness can be proposed. In such a case, however, the number of heavy wires or connectors is increased and then manufacturing costs are raised.
Furthermore, in this structure, it is necessary to bend the bus bars 57 many at many locations to connect the housing 53b with the leg portion 59a, 59b of the fusible link 58, as indicated by dotted lines in FIG. 7. Such bending formations of the bus bars 57 require accurate size control. If there are some size errors, there is fear that the bus bars 57 cannot be engaged with the main body 51. It causes some problems such as delay of operation or decreasing of manufacturing yield.